cmd/viewer: add flag to support Clone generation without Views

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/viewer/tests/tests.go

@@ -10,7 +10,7 @@ import (
 	"net/netip"
 )
 
-//go:generate go run tailscale.com/cmd/viewer --type=StructWithPtrs,StructWithoutPtrs,Map,StructWithSlices
+//go:generate go run tailscale.com/cmd/viewer --type=StructWithPtrs,StructWithoutPtrs,Map,StructWithSlices,OnlyGetClone --clone-only-type=OnlyGetClone
 
 type StructWithoutPtrs struct {
 	Int int
@@ -58,3 +58,7 @@ type StructWithSlices struct {
 	Prefixes []netip.Prefix
 	Data     []byte
 }
+
+type OnlyGetClone struct {
+	SinViewerPorFavor bool
+}

cmd/viewer/tests/tests_clone.go

@@ -196,3 +196,19 @@ var _StructWithSlicesCloneNeedsRegeneration = StructWithSlices(struct {
 	Prefixes       []netip.Prefix
 	Data           []byte
 }{})
+
+// Clone makes a deep copy of OnlyGetClone.
+// The result aliases no memory with the original.
+func (src *OnlyGetClone) Clone() *OnlyGetClone {
+	if src == nil {
+		return nil
+	}
+	dst := new(OnlyGetClone)
+	*dst = *src
+	return dst
+}
+
+// A compilation failure here means this code must be regenerated, with the command at the top of this file.
+var _OnlyGetCloneCloneNeedsRegeneration = OnlyGetClone(struct {
+	SinViewerPorFavor bool
+}{})

cmd/viewer/tests/tests_view.go

@@ -15,7 +15,7 @@ import (
 	"tailscale.com/types/views"
 )
 
-//go:generate go run tailscale.com/cmd/cloner  -clonefunc=false -type=StructWithPtrs,StructWithoutPtrs,Map,StructWithSlices
+//go:generate go run tailscale.com/cmd/cloner  -clonefunc=false -type=StructWithPtrs,StructWithoutPtrs,Map,StructWithSlices,OnlyGetClone
 
 // View returns a readonly view of StructWithPtrs.
 func (p *StructWithPtrs) View() StructWithPtrsView {